1. Field of the Invention
The present invention relates to an enhanced refrigerant recovery system, and more specifically to a refrigerant recovery system in which the recovery of refrigerant gas is maximized and non-condensable contamination is minimized.
2. Discussion of the Related Art
In refrigeration systems operating at below atmospheric pressures, various non-condensable gases, including air, often leak into the system. These gases increase the pressure in the condenser, require a high power input to the compressor, and can corrode the machinery of the system. The overall effect is a decrease in the heat transfer effectiveness and performance of the refrigeration system.
Various methods and systems have been devised to remove these non-condensable gases from the refrigeration system. Generally, the non-condensables are drawn from the condenser to a purge apparatus. The purge apparatus separates refrigerant vapor from the non-condensable gases. The refrigerant vapor is then cooled and condensed by, for example, air, water, or liquid refrigerant, and returned to the system. The separated non-condensable gases are then purged to the atmosphere. However, some amount of refrigerant vapor is typically also purged to the atmosphere along with the non-condensable
In order to further enhance the efficiency of removing the refrigerant from the non-condensable gases, an adsorbent material filled tank has been used. Such a tank has been connected to the outlet of the purge apparatus to receive the purged mixture of non-condensable gases and refrigerant vapor. An appropriate adsorbent material, such as granulated carbon, is within the tank and adsorbs the refrigerant vapor as non-condensable gases vent to the atmosphere. The adsorbed refrigerant vapor is then recovered from the adsorbent material and returned to the refrigeration system by, for example, a vacuum pump. A heater attached to the tank may facilitate this refrigerant recovery process by heating the tank to more quickly desorb the trapped refrigerant from the adsorbent material. In such systems, however, additional incoming non-condensable gases and refrigerant vapor flow to the carbon tank during the time that refrigerant is recovered and the adsorbent material in the tank is reactivated. In addition, without the use of a cooling mechanism, a reduction of the adsorption capability of the carbon material results, particularly at the start of an adsorption cycle.
Another refrigerant recovery system using an adsorbent material filled tank employs a tube coil within the tank. The tube coil receives a steady flow of hot pressurized gases from the refrigeration condenser. The hot gases provide continuous separation of refrigerant gases from the adsorbent material as non-condensables vent to the atmosphere. At least some of these separated refrigerant gases, however, are discharged to the atmosphere with the non-condensable gases. In addition, the temperature of the hot gases in the tube coil will vary depending on the operation of the refrigeration system. This can lower the efficiency of the regeneration of the adsorbent material.
Refrigerant recovery systems have also used an air pump connected to the adsorbent material filled tank to draw the non-condensable gases from the tank to the atmosphere. The use of an air pump, however, can lower the pressure in the tank to below atmospheric, causing some desorption of trapped refrigerant and the release of that refrigerant to the atmosphere.